Rezumat articol ediţie STUDIA UNIVERSITATIS BABEŞ-BOLYAI

În partea de jos este prezentat rezumatul articolului selectat. Pentru revenire la cuprinsul ediţiei din care face parte acest articol, se accesează linkul din titlu. Pentru vizualizarea tuturor articolelor din arhivă la care este autor/coautor unul din autorii de mai jos, se accesează linkul din numele autorului.

 
       
         
    STUDIA MATHEMATICA - Ediţia nr.4 din 2010  
         
  Articol:   ON THE COMBINATORIAL IDENTITIES OF ABEL-HURWITZ TYPE AND THEIR USE IN CONSTRUCTIVE THEORY OF FUNCTIONS.

Autori:  ELENA IULIA STOICA. 		 
       
         
  Rezumat:  This paper is concerned with the problem of approximation of multivariate functions by means of the Abel-Hurwitz-Stancu type linear positive operators. Inspired by the work of D. D. Stancu [13], we continue the discussions of the approximation of trivariate functions by a class of Abel-Hurwitz-Stancu operators in the case of trivariate variables, continues on the unit cub K3 = [0, 1]3. In this paper there are three sections. In Section 1, which is the Introduction, is mentioned the generalization given by N. H. Abel [1] in 1826, for the Newton binomial formula and then the very important extension of this formula given by A. Hurwitz in 1902, in the paper [3]. Here is mentioned an interesting combinatorial significance in a cycle-free directed graphes given by D. E. Knuth [5]. Then is presented a main result given in 2002 by D. D. Stancu [13], where is used a variant of the Hurwitz identity in order to construct and investigate a new linear positive operator, which was used in the theory of approximation univariate functions. In Section 2 is discussed in detail the trivariate polynomial operator of Stancu-Hurwitz type associated to a function f Є C(K3), where K3 is the unit cub [0, 1]3. Section 3 is devoted to the evaluation of the remainder term of the approximation formula (3.1) of the function f(x, y, z) by means of the Stancu-Hurwitz type operator Firstly is presented an integral form of this remainder, based on the Peano-Milne-Stancu result [12]. Then we give a Cauchy type form for this remainder. By using a theorem of T. Popoviciu [8] we gave an expression, using the divided differences of the first three orders. When the coordinates of the vectors (β), (γ), (λ) have respectively the same values we are in the case of the second operator of Cheney-Sharma [2]. In this case we obtain an extension of the results from the papers [13] and [17].

Key words and phrases. Abel-Hurwitz-Stancu operators.  		 
         
     
         
         
      Revenire la pagina precedentă